Update compiler-warning-level-1-c4172.md

We demo an unusual case but not perhaps a more common case. Added it.

Author: TylerMSFT

docs/error-messages/compiler-warnings/compiler-warning-level-1-c4172.md

@@ -22,13 +22,22 @@ The following example generates C4172:
 ```cpp
 // C4172.cpp
 // compile with: /c /W1
+
+const int* func1()
+{
+    int i = 42;
+	return &i; // C4172
+}
+
 float f = 1.f;
 
-const double& func()
+const double& func2()
 // Try one of the following lines instead:
-// const float& func()
-// const auto& func()
+// const float& func2()
+// const auto& func2()
 {
+    // The problem is that a temporary is created to convert f to a double.
+    // C4172 in this case refers to returning the address of a temporary
     return f;   // C4172
 }
 ```